Quality Video Conferencing over a network is becoming more and more desirable in businesses and education as well as for personal use. Video Conferencing is a many-to-many relationship, but also includes video telephony and distance education. Presently, there are two main types of audio/video conferencing. First is desktop audio/video conferencing, where a small camera is typically placed on top of a personal computer (PC) or workstation and video is usually displayed in a small window, potentially with shared applications (such as a shared whiteboard). The second type of video conferencing is studio based audio/video conferencing. Here, a room is specially equipped for video conferencing with one or more cameras, microphones, large monitors and possibly other equipment; such as an overhead camera for document viewing (Type 1 is typically software based; type 2 is typically hardware based). The room in which studio conferencing occurs may not be specifically for this purpose. Instead, a standard seminar room with portable equipment may be used. Typically, this type of conferencing is used for formal meetings.
Currently, networks and video conferencing function on a unicast-based technology. Therefore, the internet ends up being a best effort network that has high bandwidth requirements, significant packet loss, packet delay variation, quality degradation and time expenses. As a result, end users have become accustomed to the lack of quality in audio/video data transmission and the constant waiting for the data to be received.
As mentioned, typically, the transmission of full motion video across any computer network, such as, WAN, LAN, CAN, WAP, is achieved using unicast technology. Unicast depends on compression and decompression algorithms in order to transmit vast amounts of video/audio data. Further, unicast requires delay times for buffering video, which is the ability to pre-load portions or all of the video onto a computer for viewing. Also, there is a loss of video quality when compression of the video is used. The problems accompanying such transmission can only be achieved by:
1) hardware modifications
2) bulky deployment
3) high bandwidth availability
4) large computer processor availability
5) need for compression of video data
More importantly, the ability to simultaneously video conference more than 3 participants of the video conference poses a challenge.
Compression and decompression costs a lot of time and computer resources. Compression also degrades the quality of the video/audio data. Over the years, end users accepted slow speed and poor video quality. With respect to audio, certain codecs like MP3 provide more speed but less quality. WAV provides better quality but less speed. Thus, each time a user downloads video/audio from the internet, the user necessarily trades off some aspect of performance.
The use of video compression and decompression to transfer video data from one source to another requires a sufficient amount of time and the result is poor quality. Therefore, video conferencing to a large number of participants becomes almost impossible in a unicast environment. In this situation, as well as many others, a multicast environment would alleviate the above mentioned problems with its low bandwidth usage and time efficiency benefiting any network.